Homogeniser

ABSTRACT

A homogeniser ( 1 ) including: a housing; a drive mechanism ( 3 ) located within said housing ( 2 ); and a cutting element ( 4 ) attached to said drive mechanism ( 3 ), characterised in that at least part of said drive mechanism ( 3 ) is reversibly movable within said housing ( 2 ) between a position in which said cutting element ( 4 ) is located within said housing ( 2 ) and a position in which the cutting element ( 4 ) at least partially projects outside said housing ( 2 ) and thereby cleaning of same.

TECHNICAL FIELD

The present invention relates generally to a homogeniser and inparticular a mechanism for cleaning same and method of performing thesaid cleaning.

BACKGROUND ART

Homogenisers are used in various applications to puree, pulp pulverize,blend and otherwise homogenise a substance ranging from liquids such asmilk wherein the fat content is emulsified to render the milk of auniform consistency, to solids and semi-solid matter such as meatsamples. Homogenisers generally employ a high speed rotating cuttingimplement which reduces the sample to particles and disperses themthroughout the fluid/slurry formed from the original sample. Whilst somesamples may be substantially liquid, others are samples aresignificantly gelatinous, fibrous and/or otherwise difficult to reducecompletely to liquid form.

In laboratory testing conducted on these samples, small volumes of meatsubstance are required to be homogenised to extract meat fluids on whichthe tests are performed. At present, homogenisers employed for this taskquickly become clogged and require cleaning due to the fibrous nature ofthe sample. The avoidance of cross-contamination also requires thecleaning of the homogenizer between each sample. As the costeffectiveness of laboratory tests and the efficiency of same depend onthe speed in which the large numbers of test can be formed, anyreduction in the cleaning time of the homogeniser is clearly desirable.

To clean known homogenisers currently employed in comparable tasks, itis necessary to at least partially dismantle the homogeniser housing andmotor unit in order to extract the cutting element. Clearly this isdisadvantageous in both practical and economic terms. To avoid crosscontamination the most commercial companies require test samples to besterilised to a level termed a gross clean (99.5% clean) rather thanautoclaving between every sample. Currently, the cycle time for cleaningthe homogeniser can be at least 1-2 minutes or more.

In order to be cleaned, the homogeniser unit needs to be removed fromthe motor, the cutting element removed from the housing and the cleaningoperation performed. Not only is this process unduly protracted, thesteps involved do not readily lend themselves to automation.

There exists the need for improved means of cleaning the homogeniserwithout dismantling the unit with a reduced cleaning cycle time.

None of the known prior art addresses these needs. More specifically:

U.S. Pat. No. 6,193,404 CALANGE discloses a portable hand-held electricblender in which the novel features relate to the ability to detach therotating tool and surrounding housing for cleaning purposes. Whilst thisdoes facilitate cleaning of the rotor tool, the process istime-consuming and not intended for automation. Furthermore, there is nodisclosure of a means of extending the tool/rotor outside thesurrounding housing while still being attached to the electric drive.

U.S. Pat. No. 5,863,118 ACRELS ET AL discloses a hand-held domesticblender primarily for food preparation and the like and provides a meansof varying the actual length of the blender housing/shaft to optimiseuse in differing configurations of container. To achieve this aim, aslidable coupling arrangement permits the rotating tool/shaft head to beextended away from the motor to increase the effective length of theblender. However, there is no disclosure of projecting the tool/rotorhead outside of the housing for rapid cleaning purposes.

U.S. Pat. No. 6,186,056 BRUNO ETAL discloses a further food processingtool operating on broadly similar principles to conventional hand-heldblenders. This invention is specifically directed towards thedifficulties in cleaning such devices and sealing the rotatingparts/motor from product ingress. However, this is achieved by therelatively time-consuming process of detaching the rotating blade fromthe housing/shaft drive by means of a specialised tool.

U.S. Pat. No. 6,293,691 REBORDOSA ETAL describes a handheld foodblending device with a protective shield surrounding the rotor blade.The shield is movable to enable the rotor head to be positioned atdifferent points within the shield so as to interact more efficientlywith food of different sizes. However, there no disclosure of a means toproject the rotor head outside the shied to facilitate rapid cleaning.

U.S. Pat. No. 6,398,403 REBORDOSA ET AL also discloses a hand-helddomestic blender, incorporating a rotor blade guard configured with awall configuration composed of repeating undulations and recesses.Although the guard wall shape is designed to enhance the recirculationand consequent comminution of the food, there is no teaching of anyimprovement in the manner of cleaning said device and in particular, noteaching of projecting the rotor blade outside the guard wall forcleaning.

U.S. Pat. No. 6,523,990 LEE relates to improvements in the shaftmounting of the motor in a hand-held domestic blender. Whilst therotor-shaft/motor coupling is described in detail, there is nodisclosure of any feature capable of improving the speed of manner ofcleaning the blender. In particular, there is no disclosure ofprojecting the rotor blade outside the guard wall for cleaning.

All references, including any patents or patent applications cited inthis specification are hereby incorporated by reference. No admission ismade that any reference constitutes prior art. The discussion of thereferences states what their authors assert, and the applicants reservethe right to challenge the accuracy and pertinency of the citeddocuments. It will be clearly understood that, although a number ofprior art publications are referred to herein, this reference does notconstitute an admission that any of these documents form part of thecommon general knowledge in the art, in New Zealand or in any othercountry.

It is acknowledged that the term. ‘comprise’ may, under varyingjurisdictions, be attributed with either an exclusive or an inclusivemeaning. For the purpose of this specification, and unless otherwisenoted, the term ‘comprise’ shall have an inclusive meaning—i.e. that itwill be taken to mean an inclusion of not only the listed components itdirectly references, but also other non-specified components orelements. This rationale will also be used when the term ‘comprised’ or‘comprising’ is used in relation to one or more steps in a method orprocess.

It is an object of the present invention to address the foregoingproblems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will becomeapparent from the ensuing description which is given by way of exampleonly.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided ahomogeniser including:

-   a housing;-   a drive mechanism located within said housing; and-   a cutting element attached to said drive mechanism,    characterised in that at least part of said drive mechanism is    reversibly movable within said housing between a position in which    said cutting element is located within said housing and a position    in which the cutting element as at least partially projects outside    said housing and thereby facilitating cleaning of same.

According to another aspect of the present invention there is provided ahomogeniser substantially as described above wherein said housingincludes an outer projection with a bearing surface capable of engagingwith one or more objects external from the homogeniser to therebyrestrain movement of said housing whilst allowing said drive mechanismand cutting element assembly to be movable with respect to said housing.

According to one embodiment, the housing is a substantially tubularcylinder open at a first end. Preferably during homogenising operations,the cutting element is located at said first end within the volume ofthe cylinder boundaries.

Preferably, the housing at said first end includes a plurality of slotsand/or apertures. In one embodiment, the slots/apertures are a series ofcastellations radially disposed about said first end of the cylinder.The cutting element may preferably be formed from one or more blades.

According to one aspect of the present invention, the said outerprojection is an annular flange, preferable located about asubstantially intermediate point between the ends of said cylindricalhousing. Preferably, at least one said external object is a circular orpart-circular opening. In one embodiment, the circular opening isprovided by an open-end of a substantially cylindrical vessel. It willbe appreciated however, that many alternative configuration of externalobject are possible, and as such fall within the scope of the invention.

As used herein, the term homogeniser includes any device capable ofblending, stirring, mixing, pureeing, and/or chopping a sample intosmaller constituent particles.

The term ‘drive mechanism’ used herein refers to any appropriate meansof providing powered movement to the cutting element and/or a linkagethereto, including (but not limited to) electrical, pneumatic,hydraulic, inductive powered drives and/or mechanical,electromechanical, electrical, or other power linkage or transmissionmeans and the like.

In one embodiment, said reversibly movable drive mechanism or partthereof within said housing is formed as one stator of two-statorelectric motor, the other stator being fixed to the electric motorand/or said housing.

Whilst typical homogeniser configurations used for preparing scientificsamples for analysis are essentially devices with elongated cylindricalhousings, the invention should not be seen as being limited to same.

The present invention may operate in a conventional manner to that ofknown homogenisers when homogenising a substance. However, when adifferent sample is to be homogenised without the risk ofcross-contamination, or when the homogeniser cutting element becomesunacceptably clogged, some form of cleaning must be performed.

The cleaning action may be performed by a variety of means. In oneembodiment, cleaning is performed by spraying cleaning fluid over thecutting element when positioned at least partially projecting outsidesaid housing. Alternative cleaning means include, but are not limitedto, immersing the cutting element in a cleaning agent, the use ofcleaning swabs, pads, brushes and so forth.

One or a plurality of cleaning nozzles may be used to apply jets ofcleaning fluid, preferably under pressure to dislodge any residualsample material adhered to the cutting element. Preferably, the cleaningnozzles are located in said external object configured as asubstantially cylindrical vessel. It will be appreciated however, thatthe external object engaging the said bearing surface need notnecessarily form part of the cleaning mechanism itself.

Unless the cutting element can be moved outside the homogeniser housing,the cleaning of same will be impeded. The speed and ease by which thisconfiguration may be achieved impacts on the efficiency of the cleaningprocess. Current cleaning processes for comparable homogenisers used inthe repeated preparation of samples to a laboratory standard involve thedismantling of the drive mechanism and/or detachment of the cuttingelement. This is clearly time-consuming, potentially requiring a degreeof physical dexterity is subject to inevitable cycle time fluctuationsand requires the input of an appropriately trained operative. Thus,automating the cleaning process, or at least providing increasedconsistency, repeatability and reduced cycle times is desirable.

During sequential preparation of numerous samples for laboratory testingrequiring the homogenising of each sample, the cycle time required toperform cleaning is a key factor. The ability to automate cleaning ofthe homogeniser reduces the cleaning cycle time, increases consistency,reducing the need for manual intervention and potentially increasescleanliness. The present invention lends itself to use in an automatedcleaning process.

Thus, according to a further embodiment, the present invention providesa method of cleaning a homogeniser cutting element, said homogeniserincluding,

-   -   a housing with an outer projection configured with a bearing        surface;    -   a drive mechanism located within said housing with said cutting        element attached to the drive mechanism,        at least part of said drive mechanism being reversibly movable        within said housing between a position in which said attached        cutting element is located within said housing and a position in        which the cutting element is as at least partially projects        outside said housing,        said method characterized by the steps of    -   restraining movement of said housing by engaging said bearing        surface with a fixed external object;    -   moving said drive mechanism and cutting element assembly with        respect to the housing until the cutting element at least        partially projects from the housing; and    -   cleaning the cutting element.

Optionally, said drive mechanism is operated during cleaning to pulse,agitate or otherwise move the cutting element.

According to a further embodiment, said method step of restrainingmovement of said housing is accomplished by inserting the homogeniserinto an opening in a cleaning vessel until said bearing surface contactssaid opening.

Preferably, said cleaning of the cutting element is performed by nozzleslocated within the cleaning vessel spraying cleaning fluid across thecutting element.

Furthermore, said cleaning nozzles and/or the homogeniser may move oroscillate with respect to each other during cleaning.

Thus, the present invention provides a homogeniser which is effectiveand efficient in operational use, which reduces maintenance costs, andwhich by virtue of its construction permits the cutting element to bereadily cleaned without dismantling.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from thefollowing description which is given by way of example only and withreference to the accompanying drawings in which:

FIG. 1 shows a perspective view of a preferred embodiment of the presentinvention in the form of a homogeniser;

FIG. 2 shows an exploded perspective view of the homogeniser shown inFIG. 1;

FIG. 3 shows a side elevation of the homogeniser shown in FIG. 1 in anoperating configuration used during homogenization;

FIG. 4 shows a section along the line AA of the homogeniser shown inFIG. 3;

FIG. 5 shows a side elevation of the homogeniser shown in FIG. 1 withthe cutting element projecting from the homogeniser in a configurationused during cleaning;

FIG. 6 shows a section along the line BB of the homogeniser shown inFIG. 5; and

FIG. 7 shows a section through the homogeniser shown in FIGS. 1-6inserted into a vial for containing a sample substance to behomogenised.

BEST MODES FOR CARRYING OUT THE INVENTION

In FIGS. 1-6, a preferred embodiment of the present invention in theform of a homogeniser (1) is shown for the purposes of explanation andillustration. The homogeniser (1) is composed of a housing (2), a drivemechanism (3) and a cutting element in the form of a rotor tip (4).

The housing (2) is formed as a substantially elongated cylindricalsleeve having a first and second open end. At the first end, a rotorguard (5) is located, comprised of a tubular extension of the housing(2) adjacent to the rotor tip (4) with a plurality of slots orcastellations (6) equidistantly disposed about the circumference of thedistal end. In FIGS. 1, 3 and 7, the rotor tip (4) is shown in itsoperating position, i.e. as used during homogenisation of a samplematerial. In use, the rotor tip does not protrude beyond the extremitiesof the rotor guard (5) as this may lead to injury to the operator ordamage to the container holding the sample material (not shown).

In the preferred embodiment shown in the drawings the homogeniser (1) isattached to an electric motor (not shown) to provide power duringhomogenisation. The electric motor provides rotational movement to therotor tip (4) via the drive mechanism (3) located within, and extendingfrom, the housing (2). This may be more clearly seen in FIG. 2 showingan exploded view of the homogeniser (1) components. The drive mechanism(3) is comprised of numerous sub-components including a rotatable shaft(7) orientated along the longitudinal axis of the homogeniser (1). Oneend of the rotatable shaft (7) located towards the first end of thehousing (2) releasably engages with the rotor tip (4) whilst the otherend (towards the second end of the housing (2)) engages with theelectric motor drive (not shown).

The end of the rotor shaft (7) distal from the rotor tip (4) ispositioned inside a substantially cylindrical stator (8) which is itselfrotatably located in the housing (2) by a tubular bush (9). Thisconfiguration permits the motor (not shown) to provide rotational motionvia the stator (8), and the rotor shaft (7), to the rotor tip (4).

During homogenising operation, the sample material to be homogenised issucked in through the base of the unit, reduced to particles by theaction of the rotor tip (4) and expelled laterally outwards through thecastellations/gratings (6) of the rotor guard (5).

This action is directly comparable to existing homogenisers of this typeand is particularly suited for use in laboratory testing situationsutilizing small sample volumes with the requirement for nocross-contamination between samples. The homogeniser embodiment shown inthe drawings is particularly suitable for use with homogenising fibrous,stringy and or gelatinous material such as meat samples which need to behomogenised in order to extract meat fluids on which tests may bepreformed. It will however be understood that the invention need not benecessarily be limited to same and that alternative applications and/orconfigurations are possible and fall within the scope of the invention.

As may be seen from FIGS. 2, 4, 6 and 7, the drive mechanism (3) isspring-mounted within the housing (2) by means of a coiled spring (10)which acts (at one end) against a spring locator flange (11) and (at theother end) against a stop within the housing (2). The action of thespring (10) acts to maintain the drive mechanism (3) and attached rotortip (4) in the retracted position used during homogenisation.

The application of a force along the longitudinal axis of thehomogeniser towards the rotor tip (4) would cause movement of the entirehornogeniser (1) unless otherwise restrained. If the housing (2) isfixed by some means, the drive mechanism (3) together with the attachedrotor tip (4) is able to slid within the housing (2) against theresistive force of the closed spring (10) until the spring (10) becomescoil bound or encounters an internal stop/obstruction. The movement ofthe drive mechanism (3) within the housing (2) causes rotor tip (4)attached to rotor shaft (7) to extend beyond the rotor guard (5).

This facilitates cleaning of the rotor tip (4) in particular and therotor guard (5) and lower housing (2) in general. Dependant on the typeof sample material being homogenised, the recesses between the rotor tip(4) and the cavity guard (5) can be prone to collection of detritus,sample fibres and the like. Cleaning this region is clearly hinderedunless the rotor tip (4) is moved out of the confined of the rotor guard(5). This may be achieved by manually dismantling the homogeniser toremove the rotor tip (4) from the rotor shaft (7) and/or detaching therotor shaft (7) from the motor (not shown) and the housing (2). However,this is both time consuming and inefficient.

Automating the means of extending the rotor tip (4) outside the rotorguard (5) for cleaning may be performed by engaging a portion of thehousing (2) with a fixed external object (not shown) whilst applying aforce to the drive mechanism (3) along the longitudinal axis of thehomogeniser (1). An annular flange (12) is located at an intermediatepoint between the first and second ends of the housing (2), extendingoutwards substantially orthogonally from the surface of the housing (2).The annular surface of the flange (12) facing towards the rotor tip (4)acts as a bearing surface to engage with an external object to restrictthe movement of the housing (2) in a direction towards the rotor tip(4).

One convenient configuration of an external object to engage with thecircular flange (12) is the edge of a correspondingly sized circularaperture. In a preferred embodiment, the homogeniser (1) attached to amotor (not shown) is movable by automated transport means (e.g.electrical, hydraulic, or pneumatic drives) from homogenising a samplematerial in a vial (13) for example, to a cleaning station (not shown)for automated cleaning.

In one embodiment, the cleaning station is comprised of a substantiallycylindrical vessel apertured at one end, into which the homogeniser (1)is inserted (rotor tip (4) first) until the flange (12) contacts theaperture surrounds. Further application of force in the direction ofinsertion leads the movement of housing (2) to be constrained by thecontact with the cleaning vessel. However, the drive mechanism (3) andattached rotor tip (4) are free to move until the spring (10) becomescoil bound (as shown in FIG. 6) leaving the rotor tip (4) protrudingoutside the rotor guard (5).

Cleaning of the homogeniser (1) may be undertaken by any convenientmeans, though it has been found effective to utilize jets of cleaningfluid sprayed across the relevant portions of the rotor tip (4), rotorguard (5) and housing (2). During the cleaning action, the motor may bepulsed to agitate the rotor tip (4) to further facilitate theeffectiveness of the cleaning jets.

The cleaning vessel may be configured such that when the homogeniser isinserted through the open aperture of the cleaning vessel until therotor tip (4) is exposed, the flange (12) substantially seals the voidbetween the cleaning vessel and the housing (2), thereby preventingsplashing, spray and the like. Further enhancements to the cleaningprocess include moving one or both of the cleaning jets and or thehomogeniser in a reciprocating manner.

The rapidity and ease of use by which the homogeniser (1) may be cleanedmay be utilized in a number of applications. One particular application(not shown) is the incorporation of the homogeniser (1) in an automatedsample testing system comprised of a rotating carousel on which aplurality of vials (15) are moved between a number of stations. In oneconfiguration, the carousel may include:

-   -   a vial loading/unloading station;    -   a homogeniser station;    -   a filter station; and    -   a testing station.

The vial loading/unloading station would supply fresh samples of meatportions for example in individual vials and remove the used vials onwhich testing had been conducted. Any convenient means of effecting thevial transfer may be employed as a servo-operated robotic arms and thelike.

The homogeniser station may employ a homogeniser as per the presentinvention whose movement is also controlled by a robotic arm. Thehomogeniser would be inserted into a new vial to homogenise the sampleand then extracted, and moved to an adjacent cleaning station. The actof inserting the homogeniser into the cleaning station causes thecutting element to be projected outside the homogeniser housing tofacilitate cleaning as described above. The cleaned homogeniser is theninserted into a new sample vial and the sequence is repeated.

The homogenised vial is then rotated in the carousel to the filterstation where a filter is inserted in to the vial and sample fluidextracted. Due to the fibrous nature of meat samples, the filter willbecome clogged with unwanted detritus. Cross contamination betweensamples is also undesirable. Thus, the filter is also cleaned betweenfiltering each sample by any suitable means.

The filtered sample fluid is then passed to the appropriate testingapparatus and the entire process repeated. Such a system permits rapidcycle times, enabling large sample batches to be efficiently processedwith of greater consistency to previous systems. Furthermore, theconcatenation of the entire time taken to process all the samplesensures minimal effects from differing environmental or climaticvariations during the testing procedure.

It will be appreciated by one skilled in the art that there are manyvariations in homogeniser configuration, application, and implementationwhich fall within the scope of the present invention.

The drive mechanism described with respect to the embodiment shown inthe drawings is a mechanical power transfer means for transmitting therotational movement of an electric motor to the cutting element.However, the homogeniser housing itself may incorporate an electricmotor, the rotor shaft may be extended by a screw motion instead of apurely linear action, to give just two possible variants. All suchvariants would nevertheless give the ability to extend the cuttingelement from its surrounding housing for cleaning without necessarilyrequiring manual intervention, nor the dismantling of the homogeniser toeffect cleaning.

Aspects of the present invention have been described by way of exampleonly and it should be appreciated that modifications and additions maybe made thereto without departing from the scope thereof.

1. According to one aspect of the present invention there is provided ahomogeniser including a housing; a drive mechanism located within saidhousing; and a cutting element attached to said drive mechanism,characterised in that at least part of said drive mechanism isreversibly movable within said housing between a position in which saidcutting element is located within said housing and a position in whichthe cutting element at least partially projects outside said housing andthereby facilitating cleaning of same.
 2. A homogeniser as claimed inclaim 1, wherein said housing includes an outer projection with abearing surface capable of engaging with one or more objects externalfrom the homogeniser to thereby restrain movement of said housing whilstallowing said drive mechanism and cutting element assembly to be movablewith respect to said housing.
 3. A homogeniser as claimed in any one ofthe claim 1 wherein the housing is a substantially tubular cylinder openat a first end.
 4. A homogeniser as claimed in claim 3, wherein duringhomogenising operations, the cutting element is located at said firstend within the volume of the cylinder boundaries.
 5. A homogeniser asclaimed in claim 3, wherein the housing at said first end includes aplurality of slots and/or apertures.
 6. A homogeniser as claimed inclaim 5, wherein the slots/apertures are a series of castellationsradially disposed about said first end of the cylinder.
 7. A homogeniseras claimed in claim 1, wherein the cutting element is formed from one ormore blades.
 8. A homogeniser as claimed in claim 2, wherein the saidouter projection is an annular flange, preferably located about asubstantially intermediate point between the ends of said cylindricalhousing.
 9. A homogeniser as claimed in claim 2, wherein at least onesaid external object is a circular or part-circular opening.
 10. Ahomogeniser as claimed in claim 9, wherein the circular opening isprovided by an open-end of a substantially cylindrical vessel.
 11. Ahomogeniser as claimed in claim 1, wherein said reversibly movable drivemechanism or part thereof located within said housing is formed as onestator of two-part stator electric motor, the other stator being fixedto the electric motor and/or said housing.
 12. A method of cleaning ahomogeniser cutting element, said homogeniser including, a housing withan outer projection configured with a bearing surface; a drive mechanismlocated within said housing with said cutting element attached to thedrive mechanism, at least part of said drive mechanism being reversiblymovable within said housing between a position in which said attachedcutting element is located within said housing and a position in whichthe cutting element at least partially projects outside said housing,said method characterized by the steps of restraining movement of saidhousing by engaging said bearing surface with a fixed external object;moving said drive mechanism and cutting element assembly with respect tothe housing until the cutting element at least partially projects fromthe housing; and cleaning the cutting element.
 13. A cleaning method asclaimed in claim 12, wherein said drive mechanism is operated duringcleaning to pulse, agitate or otherwise move the cutting element.
 14. Acleaning method as claimed in claim 12, wherein said method step ofrestraining movement of said housing is accomplished by inserting thehomogeniser into an opening in a cleaning vessel until said bearingsurface contacts said opening.
 15. A cleaning method as claimed in claim14, wherein said cleaning of the cutting element is performed by nozzleslocated within the cleaning vessel spraying cleaning fluid across thecutting element.
 16. A cleaning method as claimed in claim 14, whereinsaid cleaning nozzles and/or the homogeniser may move or oscillate withrespect to each other during cleaning. 17-18. (canceled)